So I did play Toy World 1 Reverse (Platinum Cup) when I suddenly had an intense blue strobe light effect on my screen until about the end of the corresponding lap. It looked similar to the Star pulse item's effect but neither was the stationary one on the map used nor was a star pulse used at all. I'll link to a video with the timestamp so you can look at what I mean.

I've had this happen a couple of times over the years as well. Seems streamable ate one of the clips I had, but video of the end of another instance. I think it's come up on the discord a few times as well, but both times I've had it happen it:
- was offline, single-player
- both on TW1 (once on normal course, once on reverse)
- effect lasted somewhere between 10 and 20 seconds
- effect paused when game was paused
- occurred right near the end of the race (looking at that clip, probably less correlation)

Just as a curiosity, do you have a replay? And for anyone else who does run into this, under what circumstances did it happen (track, gamemode etc)?